# US 5,700,362 A · Method of treating copper foil for printed circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,362 A - Document ID: US5700362A - Status: Granted - Kind: A - Application number: 08/666,030 - Filed: 1996-06-19 - Granted: 1997-12-23 - Earliest claimed: 1994-04-15 - Assignees: Fukuda Metal Foil & Powder Co., Ltd. - Inventors: Masami Yano; Masato Takami - Web page: https://patentgrep.com/patent/US5700362A ## CPC - H05K 3/244: {Finish plating of conductors, especially of copper conductors, e.g. for pads or lands (selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3465)} - C23C 22/68: using aqueous solutions with pH between 6 and 8 - C25D 3/565: {containing more than 50% by weight of zinc} - H05K 3/282: {for inhibiting the corrosion of the circuit, e.g. for preserving the solderability} - H05K 3/384: {by plating} - H05K 3/389: {by the use of a coupling agent, e.g. silane} - H05K 2201/0355: Metal foils - H05K 2203/0723: Electroplating, e.g. finish plating - H05K 2203/124: Heterocyclic organic compounds, e.g. azole, furan - Y10T 428/12438: Composite - Y10T 428/12556: Organic component - Y10T 428/12792: Zn-base component - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A copper foil for printed circuits of which a shiny side has resin dust resistance, excels in heat discoloration resistance and rust preventiveness, and does not adversely affect the solderability and resist adhesion, and a method of treating the surface of such copper foil. The copper foil for a printed circuit comprises a first layer of zinc alloy composed of zinc and nickel and/or cobalt, formed on the shiny side surface of a copper foil, and a second layer composed of a mixture or compound of benzotriazole derivative and phosphorus compound (and silicon compound) formed on the layer. The method for treating the surface of a copper foil for a printed circuit comprises the steps of forming a first layer of zinc alloy composed of zinc and nickel and/or cobalt by electroplating on the shiny side surface of a copper foil, and forming a second layer by immersing it in an aqueous solution of benzotriazole derivative and phosphorus compound (and silicon compound). ## Claims ### Claim 1 A method for surface treating cooper foil having a shiny side for printed circuits comprising: a step of forming a first layer of a zinc alloy of zinc and nickel and cobalt by electroplating the shiny side surface of said copper foil, and a step of forming a second layer by immersing the first layer in an aqueous solution bath containing benzotriazole derivative and a phosphorus compound. ### Claim 2 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the second layer is formed by immersing in an aqueous solution bath containing the benzotriazole derivative, the phosphorus compound, and a silicon compound. ### Claim 3 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein the silicon compound is selected from the group consisting of a silane coupling agent, silicic acid, metasilicic acid, and silicic acid alkaline metal salt. ### Claim 4 (depends on 3) A method of surface treating copper foil having a shiny side for printed circuits of claim 3, wherein the silane coupling agent is selected from the group consisting of .tau.-amino propyl triethoxy silane, N-.beta.-amino ethyl-.tau. -amino propyl trimethoxy silane, .tau.-glycidoxy propyl trimethoxy silane, .tau.-glycidoxy propyl methyl diethoxy silane, and .tau.-ureidopropyl trimethoxy silane. ### Claim 5 (depends on 3) A method of surface treating copper foil having a shiny side for printed circuits of claim 3, wherein the silicon compound is in an aqueous solution with Si content of 0.01 to 1 g/liter. ### Claim 6 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein a ratio by mol of zinc ions, nickel ions and cobalt ions is in a range of Zn/(Co+Ni)=0.5 to 5.0. ### Claim 7 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein a pH of an electrolytic treating bath is 3 to 5. ### Claim 8 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein the benzotriazole derivative is selected from the group consisting of benzotriazole, tolyl triazole (methyl benzotriazole), hydroxy benzotriazole, and carboxyl benzotriazole. ### Claim 9 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein the benzotriazole derivative is in the aqueous solution at a concentration of from 0.01 to 10 g/liter. ### Claim 10 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein the phosphorus compound is selected from a group consisting of trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, lithium phosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, phosphoric acid, and sodium hypophosphite. ### Claim 11 (depends on 10) A method of surface treating copper foil having a shiny side for printed circuits of claim 10, wherein the phosphorus compound is in an aqueous solution with phosphorus content of 0.005 to 5 g/liter. ### Claim 12 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein a pH of the aqueous solution bath containing the benzotriazole derivative, the phosphorus compound, and the silicon compound is 5 to 11. ### Claim 13 (depends on 2) A method of surface treating copper foil having a shiny side for printed circuits of claim 2, wherein the benzotriazole derivative is in the aqueous solution at a concentration of from 0.2 to 3 g/liter. ### Claim 14 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the zinc alloy is formed in the following electrolytic bath and electrolytic conditions: ______________________________________ ZnSO.sub.4.7H.sub.2 O 0.02 to 0.30 mol/l (5.8-86 g/l) NiSO.sub.4.6H.sub.2 O 0.004 to 0.30 mol/l (›0! 1.1-79 g/l) COSO.sub.4.7H.sub.2 O 0.004 to 0.30 mol/l (›0! 1.1-84 g/l) CH.sub.3 COONa.3H.sub.2 O 5 to 50 g/l pH 3.0 to 5.0 Bath temperature 25 to 35.degree. C. Current density 0.1 to 1.0 A/dm.sup.2 Quantity ›if! of electricity is 0.5 to 2.0 coulombs/dm.sup.2. ______________________________________ ### Claim 15 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein a ratio by mol of zinc ions, nickel ions and cobalt ions is in a range of Zn/(Co+Ni)=0.5 to 5.0. ### Claim 16 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein a pH of an electrolytic treating bath is 3 to 5. ### Claim 17 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the benzotriazole derivative is selected from the group consisting of benzotriazole, tolyl triazole (methyl benzotriazole), hydroxy benzotriazole, and carboxyl benzotriazole. ### Claim 18 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the benzotriazole derivative is in the aqueous solution at a concentration of from 0.01 to 10 g/liter. ### Claim 19 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the phosphorus compound is selected from a group consisting of trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, lithium phosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, phosphoric acid, and sodium hypophosphite. ### Claim 20 (depends on 19) A method of surface treating copper foil having a shiny side for printed circuits of claim 19, wherein the phosphorus compound is in an aqueous solution with phosphorus content of 0.005 to 5 g/liter. ### Claim 21 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein a pH of the aqueous solution bath containing the benzotriazole derivative and the phosphorus compound is 5 to 11. ### Claim 22 (depends on 1) A method of surface treating copper foil having a shiny side for printed circuits of claim 1, wherein the benzotriazole derivative is in the aqueous solution at a concentration of from 0.2 to 3 g/liter.